Influenza Incubation

. Introduction-causal-agent
Equine influenza (EI) is caused by a type A orthomyxovirus. The virus 80-120 nanometers (nm) in diameter, and consists of a core of eight separate segments of single stranded ribonucleic acid (RNA) surrounded by an arrangement spike glycoproteins. These viruses are classified according to the relative number of the hemagglutinin (H) and neuraminidase (N) glycoproteins in the outer lipid layer. Strains (or types) of flu virus are formally described according to type (A, B or C), host species, location of first isolation (city or country), strain number (if applicable) The year of the first isolation and antigenic subtype (H and N designation), the shorthand methods of identification are limited to the H / N description. The two main strains known to cause disease in equines are H7N7 (A/eq/Prague/56 [H7N7] influenza type A, horses, first isolated in Czechoslovakia in 1956) and H3N8 (A / eq/Miami/2/63 [] H3N8 type A influenza, equine, first isolated in Miami, strain 2, isolated in 1963). The two subtypes are immunologically distinct. Subject lines of the two main strains (eg, A/eq/Newmarket/2/93] H3N8 [, A/eq/Kentucky/92 [N3H8]) have emerged due to antigenic shift (reassortment of the genome resulting from genetic modification) and antigenic drift (point mutations in the genetic code causing minor changes in the H and N glycoproteins).
Natural distribution
Equine influenza affects horses, donkeys, mules and other equines. The virus is widespread, with only Iceland, New Zealand and Australia, considered free of the virus. The H7N7 subtype is considered extinct or present at very low levels. The H3N8 subtype appears to be a mutation of an outbreak of avian influenza involving a change virus.An subtype H3N8 (designated A/eq/Jilin/89 [H3N8]) occurred in China in 1989. high morbidity (80%) and mortality (20%) were observed. Other major outbreaks of the H3N8 subtype occurred in the world, including the Trinity (1979), Argentina (1985), South Africa (1986) and Jamaica (1989). Most outbreaks occur at racetracks, therefore, the horse racing activities have been suspended for extended periods, which marked the economic losses. In Nepal, the disease has been reported in the year Nepalganj year 1988/1989.Same epidemic disease occurred in many of India too. Recently, Australia has recorded the appearance of the disease in many countries. Like mules and horses are used as draft animals in the remote part of many countries. In those days we all talk about how avian flu we know about it.
Transmission
Equine influenza is spread by aerosol and respiratory secretions and contaminated objects, including contaminated inanimate objects and people moving between infected and uninfected horses. The most common source of infection and outbreak is the introduction of a new animal in the herd. The incubation period is usually one to three days. The incubation period, approaching seven days have been observed, but are less frequent. Infected horses excrete the virus in respiratory secretions during the incubation period, and continue to shed virus for four to five days after clinical signs are observed. It is also possible for an infected animal to shed the virus for 7-10 days after the animal appeared to recover. Viral shedding is thought to reach its peak during the 24-48 hours the animal is febrile. Infected droplets may be able to spread as far as 50 meters. Virtually 100% of horses that are exposed become infected. Nearly 20% of infected horses show no clinical signs of disease, but still shed virus and can spread infectious morbidity and mortality
Morbidity associated with EI in naaŻve populations is estimated at 60-90% and to date, the mortality of horses with confirmed infection ranged from 1% to 20%. mortality rate was highest in foals.